Since mid-1980s, several generations of digital video coding standards have been developed by the International Telecommunications Union (ITU) Telecommunications Standardization Sector (ITU-T) Video Coding Experts Group (VCEG) and the International Organization for Standardization and International Electrotechnical Commission (ISO/IEC) Moving Picture Experts Group (MPEG). Examples of video coding standards include H.261, MPEG1, H.262 or MPEG2, MPEG4, H.263, H.264 or MPEG-AVC (Advanced Video Coding). Some of the video coding standards were actually developed jointly by the two standard organizations above. Currently, another video coding standard commonly referred to as High Efficiency Video Coding (HEVC) is under development by the Joint Collaborative Team on Video Coding (JCTVC), which is an expert group jointly created by ITU-T and ISO/IEC.
To achieve high compression efficiency for video signals, designs of video encoding and decoding architectures in some of the existing video coding formats or standards may have been largely the same or similar. Examples of such formats or standards may include those aforementioned, an open video compression format which is developed by GOOGLE and referred to as VP8, and another video compression format which is initially developed by MICROSOFT and referred to as VC-1. A typical architecture may be a hybrid of motion compensated inter-frame prediction, spatial transform coding with scalar quantization, transform coefficient scanning, and entropy encoding. Therefore, video coding standards employing such an architecture are sometimes also referred to as hybrid video coding systems.